The present disclosure relates to an X-ray tube, and more particularly, to an X-ray tube generating an X-ray, having a simple structure from which a element necessary for focusing an electron beam, such as a magnetic lens, is removed, and having a nanometer-scale focal spot.
An X-ray source (a nano focus X-ray source) having a nanometer-scale focal spot is required for a non-destructive inspection of an object having a microstructure, such as a semiconductor chip.
In general, a nano focus X-ray source includes an electron source (cathode) generating an electron beam, a focusing unit focusing the electron beam emitted from the electron source, and a target (anode) enabling the focused electron beam to collide with each other to generate an X-ray. Herein, since the electron beam travels inside the X-rays source which is in a vacuum state, a proper vacuum is maintained in a path from the X-rays source to the target by a vacuum container.
The focusing unit is composed of a lens for focusing an electron beam, etc. Since an electrostatic lens has a limitation in demagnification due to an aberration etc., a magnetic lens having one or more stages for high focusing of electron beams is used to focus the electron beam in a nano meter size. The focused electron beam collides with a target of metal material and generates a nano focus X-ray.
In general, a magnetic lens is bulky and heavy, and continuously consumes current in order to form a magnetic field. Thus, the related arts of using the magnetic lens as a focusing unit have a limitation in that an X-ray source has a bulky and heavy shape due to the magnetic lens.